CMMVC8390E Cannot set easy_tier_option for child storage pool, the value must be same as parent storage pool's easy tier setting.
Explanation
You cannot change the Easy Tier® setting of a child storage pool.
User response
If you specified the wrong storage pool, retry the command using the correct storage pool.
If you want to change the Easy Tier setting of a parent pool, use the chmdiskgrp -easytier easy_tier_option command.